Constabulary

I have googled that for you and the 1st hit when looking for a manual for this machine is this: https://www.manualslib.com/manual/482501/Brother-Db2-B755.html?page=2#manual scroll down a bit and on page 2 you find the needle system. Google result for: Leather needle

we do not know what brand or machine model you have but I´m pretty sure it is mentioned in the manual. Afaik it is for adjusting the foot height.

I do not see any disadvantages in a 2 motion (back and forth going) feed dog. I had a 2 motion Pfaff 345 binder machine and it sewed just everything... The short stitches only happened when set up for binding and feeding too thick binding material through the binder but IMO this has nothing to do with 2 or 4 motion feed since both machine have needle feed. Thats at least what I have experienced with 2 motion feed dog machines. $800 in either case is a quite good deal when I look at the condition of these two machines and when I look at the pictures both seem not to be setup as binder machines. I would probably even buy both, maybe they do a package deal and you can make some $ selling the other machine. Condition really seem to be excellent. BUT - test them before you buy them! You never know how good or bad the motor is working - at least one seem to have EFKA motors and its expensive to fix them if they are not working properly. Pfaff is marketing their 335 model work leather work. H3 machines are usually set up for heavier material and have a foot lift of approx 11mm. EDIT: Just noticed the machine in upper picture has not stitch length lever but maybe its in the drawer.

hard to tell from the picture but maybe t you have to adjust the bobbin case opener (mentioned in the manual) maybe gap between bobbin case opener / thread release finger and hook notch is too small. EDIT:

Often these machines are setup to customers specs by different companies and you do not find a manual for a particular setup. I like tinkering too (hell, I do!) but wasting time and money and not coming to an end with a setup for maybe months is just senseless. Maybe check with MJFoley http://www.mjfoleyco.com/sewing/durkopp-adler/

And how is it going here? Large hook installed?

This is the Pfaff TU and IMO the position of the tension release pin is not really obvious I´d say but just for completing here is the OEM Pfaff TU

agree but this would not cause any of the shown issues I think, this is just a thread guide with a very weak spring. and have you checked the needle bar height? Not catching the thread loop usually is a timing issue, either needle bar to high (I still think this is the problem) or hook too far away form the needle (or both). If it was me I would lower the needle bar by 0,5 - 1mm and check again. Its easy to revise if this is not the problem. Loops at the bottom are either caused by too low or none top tension or a way to high bottom tension and this is a separate problem. BTW - your tension unit looks like it is put together from different (not OEM) parts. The tension disc are not Pfaff, there is a small pin cut away which would hold the OEM Pfaff tension discs in place ( Pfaff discs have notches). The tension release disc is from different machine too. I do not say this is causing the issues (but who knows when parts are bubba'ed) but I just wanted to have it mentioned. Question: is there a small pin inside the the threaded tension post which holds the discs spring and nut? EDIT: Picture shows a non Pfaff tension unit (principles are the same) but in this picture the position of the small pin is more obvious. So is this pin present inside the threaded post? If yes and it is too long (who know since your TU is bubba'ed) it could cause a tension release. Another question: are you using a knee lifter or foot pedal for lifting the presser foot?

https://www.google.com/search?q=flat+bed+attchment+site%3Aleatherworker.net%2Fforum&ie=utf-8&oe=utf-8

that looks like a tension problem - Which picture is top and which is bottom side? I guess the flesh (rough) side is the top side right?

OH MY GOD - to be honest if you do not need all the bells & whistles - remove them and buy a plain new servo motor. I tried to re set up something similar but different motor and I gave up just too much time and money and it was not worth both IMO. My thinking back then was wow - industrial sewing stuff... so cool, will be great to use... I soon dropped this idea and the whole thing went to the junk yard - just everything including the machine. This was many many years ago and I do not regret. And I tried it a second time with a Pfaff bar tacker - same thing... it went to the junk yard. Not worth my time and money. Lesson learned. Keep things simple if you can.

Sometimes needle bar rise a little bit so w/o sitting in front of the machine I would guess you have to lower the NB a little bit. As I said before I would check the needle hook timing. Procedure is in the manual I have liked above.

settings should be the same I think. Are you sure you interst the needle correctly?

Since I see a white machine I guess it is the current 335 model. Here is a service manual for the current 335 model. It should help you with the settings: Pfaff 335 Service manual.pdf

different story but check this thread:

Often the problem is just an not correctly adjusted needle bar but hard to tell from the distance. First thing I would do is checking the correct threading and the needle hook timing. Are you sure the needle is insert correctly and using the correct needle system? I guess you have a manual for your machine, right?

The machine head seems to be refurbished Singer 29K71 - one of the best patchers you can buy IMO.

Not mine just wanted to share this. Something you don´t see very often nowadays. New in crate Singer 95K from 1950 https://www.ebay-kleinanzeigen.de/s-anzeige/singer-naehmaschine-neu-und-ovp-samler-einzelstuecke/1070067466-240-8654

Some more pictures of a vintage setup (not mine) with separate clutch and permanent motor - sorry no better pictures.

as far as I have researched, NO. https://www.wouros-partner.de/usa-ausnahmen-von-den-zusatzzoellen-fuer-sendungen-aus-china-mit-wert-unter-800-us/ they put a link and source at the end of the article. Google translate: https://translate.google.com/translate?hl=de&sl=de&tl=en&u=https%3A%2F%2Fwww.wouros-partner.de%2Fusa-ausnahmen-von-den-zusatzzoellen-fuer-sendungen-aus-china-mit-wert-unter-800-us%2F Importing goods from China to the US is not my business so please evaluate this by your self. However I would check with UPS or DHL Express in this regard in case you want to work with them. But IMO they are the easier way to import goods for small business. EDIT: cant´t read the full article but the headline pretty much tells the story: https://www.wsj.com/articles/tariffs-on-chinese-goods-are-skirted-by-some-u-s-shoppers-11577788201 EDIT II: https://www.ecomcrew.com/trumps-china-tariffs/

If I wanted to import a sewing machine form China I would do this with DHL Express or UPS. On my side of the pond they do the custom work when you provide them a regular invoice or commercial invoice (usually invoice is included in the package) and they (UPS or DHL) charge you the import fees, VAT and some fees for their work (about 10-20€ in case of DHL). They deliver the package / machine to your door when the fees are paid or they do COD. I don´t know how it works in the US but it would surprise me if it would work differently in the US. Question is how much the shipping will be. Check with UPS and check with DHL Express how they do the custom work and how much they charge. And AFAIK below $800 (not sure) they do not even charge custom fees in the US.

Clutch goes under the table but theses separate clutches are for a permanent running motor drive not for treadle drive, you do not need a clutch when you treadle. So either do away the clutch and run the machine with a modern servo motor or if you want to use the shown clutch then mount the treadle stand on a wooden frame or wooden board where you can mount the permanent running motor. This is how a permanent running motor + separate clutch set up would look like.

I just got a warning from Firefox (78.0.1) while opening LW.net. I think other users will experience this too. Warning on my end is of course in German language Seems the LW.net site is not supporting the current standard TLS 1.2 I had to reactivate TLS 1.1 to access this site. Just wanted to have it mentioned.

I haven´t yet touched a 2 needle post bed machine but I´m pretty sure you have to stick to your setup and cannot use singe needle feet because none of the needles is centered on the needle bar and the needle hole in the feed dog is also not centered (meaning in line with the foot bars + needle bar). You can remove the left or right needle and use the machine as single needle machine but thats almost it I´d say. You may (or may not ) find so called gauge sets for your post bed machine for using different needle spaces but expect high $ ($$$$$$$$$$$$$) prices and you have to change a lot of setting (f.i. moving the left and right posts - if that is possible at all). Even when you change the entire needle bar (to have a centered needle) you will not find single needle throat plates and feed dogs for a double needle machine. You probably can modify the existing foot set or buy a 2nd foot set and modify them for single needle use... Post bed machines with double needle are very special! Just my thoughts... EDIT: Maybe KHSEW.com has something... not sure what exactly fits thew 268 https://www.khsew.com

maybe it is set up for 207 - I don´t know. Sometimes needles from different machines mix up and find their way into the wrong accessory box. You would not believe what I found in accessory boxes. Best find was a Luger 08 wrench / take down tool (not kidding).